Executive Summary
A regional gravity survey of Ebonyi State was carried out in order to produce Bouguer anomaly, Free-air anomaly and the Elevation map of the State for mineral exploration.Acquisition of gravity data as a tool for mineral exploration is useful because gravity differences or anomaly reflect lateral density variation in rocks extending to several kilometres beneath the ground which interpretation reveals information about the subsurface geology.A total of 501 gravity stations were covered in an area of 5,530km2 which gives a station density of 1 in 11km2 grids. Twenty-four evenly distributed gravity base stations were established across the entire State. These base stations were tied to the International Gravity Standardization Net (IGSN ’71) of 1971 through the Primary Gravity Network of Nigeria (PGNN).Result of this survey shows a good correlation between the Bouguer anomalies and the surface geology of Ebonyi State. The dominant positive Bouguer anomaly depicts a linear structure that is likely to be a dyke and could be a host for dense mineral deposit. This linear structure trends in the NE/SW direction and stretches from Isu to Abakaliki through Ugbodo and Ndamadu and into Benue State. The Free-air anomaly map has a preferred orientation that is consistent with the general geological setting of the area.Investors in Lead Zinc, Baryte, Limestone, Salt, etc will find the Bouguer anomaly map very useful. They are advice to carry out detail investigation and modeling on some of the more important Bouguer anomalies in order to determine the geometry of the mineral ore before mining. The Free-air anomaly and the Elevation maps are recommended to surveyors and geodesists. Researchers and Investors in mineral resources carrying out gravity survey in Ebonyi State are recommended to tie their surveys to IGSN ’71 through any of the established base stations in the State. This will greatly reduce errors in gravity surveys.
